MUMBAI, India: The new technology is, to its critics, Orwellian. Others view it as a silver bullet against terrorism that could render waterboarding and other harsh interrogation methods obsolete. Some scientists predict the end of lying as we know it.

Now, well before any consensus on the technology’s readiness, India has become the first country to convict someone of a crime relying on evidence from this controversial machine: a brain scanner that produces images of the human mind in action and is said to reveal signs that a suspect remembers details of the crime in question.

For years, scientists have peered into the brain and sought to identify deception. They have shot infrared beams through liars’ heads, placed them in giant magnetic resonance imaging machines and used scanners to track their eyeballs. Since the Sept. 11 attacks, the United States has plowed money into brain-based lie detection in the hope of producing more fruitful counterterrorism investigations.

The technologies, generally regarded as promising but unproved, have yet to be widely accepted as evidence — except in India, where in recent years judges have begun to admit brain scans. But it was only in June, in a murder case in Pune, in Maharashtra State, that a judge explicitly cited a scan as proof that the suspect’s brain held “experiential knowledge” about the crime that only the killer could possess, sentencing her to life in prison.

Psychologists and neuroscientists in the United States, which has been at the forefront of brain-based lie detection, variously called India’s application of the technology to legal cases “fascinating,” “ridiculous,” “chilling” and “unconscionable.” (While attempts have been made in the United States to introduce findings of similar tests into court cases, these generally have been by defense lawyers trying to show the mental impairment of the accused, not by prosecutors trying to convict.)

“I find this both interesting and disturbing,” Henry Greely, a bioethicist at Stanford Law School, said of the Indian verdict. “We keep looking for a magic, technological solution to lie detection. Maybe we’ll have it someday, but we need to demand the highest standards of proof before we ruin people’s lives based on its application.”

Whatever American scientists think, law enforcement officials from several countries, including Israel and Singapore, have shown interest in the brain-scanning technology and have visited government labs that use it in interrogations, Indian officials said.

Methods of eliciting truth have long proved problematic. Truth drugs tend to make suspects babble as much falsehood as truth. Polygraph tests measure anxiety more than deception, and good liars may not feel anxious. In 1998, the United States Supreme Court said there was “simply no consensus that polygraph evidence is reliable.”

This latest Indian attempt at getting past criminals’ natural defenses begins with an electroencephalogram, or EEG, in which electrodes are placed on the head to measure electrical waves. The suspect sits in silence, eyes shut. An investigator reads aloud details of the crime — as prosecutors see it — and the resulting brain images are processed using software built in Bangalore.

The software tries to detect whether, when the crime’s details are recited, the brain lights up in specific regions — the areas that, according to the technology’s inventors, show measurable changes when experiences are relived, their smells and sounds summoned back to consciousness. The inventors of the technology claim the system can distinguish between peoples’ memories of events they witnessed and between deeds they committed.